Carburetor vent arrangement



E. OLSON CARBURETOR VENT ARRANGEMENT Filed Sept. 29, 1955 Dec. 8, 1959HIS IN VEN TOR.

HNER 0130" If. Maria A T T URI/i Y United States Patent CARBURETOR VENTARRANGEMENT Elmer Olson, Rochester, N.Y., assignor to General --"MotorsCorporation, Detroit, Mich., a corporation of Delaware This inventionpertains to carburetors for internal combustion engines, andparticularly to means for vent- :ing a carburetor mixture conduit toatmosphere anterior ,to the closed position of a throttle valve.

Heretofore, it has been proposed to form vent means in the throttle bodyof a carburetor anterior to the closed position of the throttle valve,by drilling a hole, or holes,

in the throttle body which connect the mixture conduit to atmosphere.Vent means of this type are disclosed in the Weldy Patent 2,690,331, andthe vent means permit the fuel vapor which collects in themixtureconduit anterior to the closed throttle valve to exhaust by gravity toatmosphere when the engine is not in operation. The incorporation ofvent means connecting the mixture conduit to atmosphere anterior to theclosed position of a throttle valve greatly facilitates the restartingof a hot engine. vent anterior to the closed position 'of a throttlevalve Without, additional machining operations such as are necessary inthe aforementioned Weldy patent. Ac-

cordingly, among my objects are the provision of a carburetor includingvent means for the mixture conduit, which vent means are locatedanterior to the closed position of a throttle valve disposed therein;and the further provision of a gasket for insertion between portions ofa carburetor mixture conduit having vent means formed therein.

The aforementioned and other objects are accomplished in the presentinvention'by forming vent means in the gasket between the carburetorfuel bowl body and the throttle body which connect the mixture conduitto atmosphere anterior to the closed position of the throttle valve.While the carburetor disclosed herein is of the four-barrel type havingtwo primary and two secondary induction mixture conduits, this is onlyexemplary, since the gasket construction could obviously be modified forThis invention relates to means for forming a 7*:

use with either single or double barrel carburetors. Spe- I cifically,the gasket of this invention is composed of fibrous material having anirregular shape, and is formed with four substantially circular openingswhich correspond to the portions of the mixture conduit in the fuel bowlcasting and the throttle body casting. The gasket is interposed betweenthe fuel bowl casting and the throttle body casting which areinterconnected by a plurality of bolts and forms a seal between the twocastingsexcept for the mixture conduit vent means.

Each primary mixture conduit opening in the gasket is formed with asubstantially radially extending slot, the inner end of which intersectsthe mixture conduit and the outer end of which is closed by theperipheral edge of the gasket.- However, a portion of each radiallyextending slot communicates with atmosphere below the fuel bowl castingand above the throttle body casting. Each secondary mixture conduitopening in the gasket is formed with a substantially tangential slot,the inner end of which intersects the mixture conduit opening and theouter end of which is closed by the gasket periphery.

2,916,271 Patented Dec. 8, 1959 However, as described in conjunctionwith the primary mixture conduits, the slots connecting with thesecondary mixture conduits are exposed to atmosphere between the fuelbowl casting and the throttle bowl casting. The vent slots in the gasketare located anterior to the closed position of the throttle valves whichare disposed in the throttle body and permit the exhaust of 'fuel vaporto atmosphere by gravity when operation of the engine is discontinuedwith the throttle valves in the closed position. 1

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing wherein a preferred embodiment of the present invention isclearly shown.

In the drawing:

Fig. 1 is a view, partly in section and partly in elevation, of acarburetor constructed according to this invention.

Fig. 2 is a sectional view taken along line 22 of Fig. 1.

Fig. 3 is a fragmentary sectional view taken along line 33 of Fig. 2.

As pointed out in the aforementioned Weldy patent, it is desirable forseveral reasons to vent the mixture conduits of a carburetor toatmosphere so that the fuel vapor which collects above the closedthrottle valves in the mixture conduits when operation of the engine isdiscontinued may exhaust to atmosphere. With reference to Fig. 1, aconventional four-barrel carburetor is depicted generally by the numeral10, the carburetor including an air horn body casting 12 within which anautomatic choke valve 14 is mounted, a fuel bowl body casting 16 and athrottle body casting 18. The air horn casting 12 is connected to thetop of the fuel bowl casting 16 by a plurality of screw fasteners 20, asuitable gasket 22 being interposed between the body members 12 and 16.Similarly, the throttle body casting 18 is formed with a flange 24 whichis connected by screw devices 52 to the lower surface of the fuel bowlmember 16, a gasket 26 being interposed between the body members 16 and18.

The fuel bowl body member 16 has formed therein a pair of primarymixture conduit portions 28 and a pair of secondary mixture conduitportions 30, which in accordance with conventional practice aresubstantially cylindrical. The throttle body member 18, likewise, hasformed therein primary mixture conduit portions 32 and secondary mixtureconduit portions 34, which are generally cylindrical, and the conduitportions in both the fuel bowl body 16 and the throttle body 18constitute the mixture passages, or conduits, of the carburetor. Theconduit portions 28 and 30 in the fuel bowl body 16 are formed with mainventuris, not shown, and fuel nozzles so as to form a combustiblemixture which is supplied to the engine, not shown, through the mixtureconduits as controlled by primary throttle valves 36 and secondarythrottle valves 38. The primary throttle valves 36 are mounted on acommon shaft 40 rotatably journaled on the throttle body 18, and thesecondary throttle valves 38 are attached to a common shaft 42,likewise, rotatably journaled in the throttle body 18.

With particular reference to Figs. 1 and 2, it will be noted that thegasket 26, composed of suitable fibrous materials, is formed with a pairof circular openings 44, which correspond to the conduit portions 28 and32 and a second pair of substantially circular openings 46, whichcorrespond to the conduit portions 30 and 34. Each primary conduitopening 4'4 on the gasket 26 is formed with a substantially radiallyextending slot 48, the outer end of which is closed by the periphery ofthe gasket, and the inner end of which intersects the opening 44. Thegasket 26 is also formed with a pair of tangentially extending slots 50,the outer ends of which are closed by the gasket periphery, and theinner ends of which intersect gasket openings 46. The slots 48 and 50constitute the vent means formed in the gasket 26, which slots areanterior to the throttle valves 36 and 38 when the throttle valves arein the closed position, as depicted in Fig. 1. As seen in Fig. 3, theupper surface of the gasket 26 engages the lower surface of the fuelbowl casting 16, While the main section of the throttle body casting 18is spaced therefrom. Accordingly, the outer portion of the slot 50communicates with atmosphere and forms a downwardly opening passagewhereby fuel vapor collecting above the closed throttle valves in themixture conduit can exhaust by gravity to atmosphere. The outer portionsof the slots 48, which communicate with the primary mixture conduits,are connected to atmosphere in the manner identical to that depicted inFig. 3. Accordingly,

when operation of the internal combustion engine is discontinued withthe throttle valves in the closed position, any fuel vapor whichcollects anterior to the throttle valves will flow by gravity throughthe vent means 48 and 50 in the gasket 26 to atmosphere.

From the foregoing it is readily apparent that the present inventionprovides simple and economical means for venting the mixture conduits ofa carburetor anterior to the closed position of throttle valves disposedtherein when the engine is not in operation. By forming the vent meansin the gasket between the fuel bowl casting and the throttle bodycasting, the necessity of additional machining operations beingperformed on the carburetor is eliminated.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. A carburetor for an internal combustion engine including, a mixtureconduit, a first body member having a portion of the mixture conduittherein, a second body member having a portion of the mixture conduittherein, a gasket interposed between said members having an openingcorresponding with the mixture conduit portions in said members, meansinterconnecting said members, a throttle valve in the mixture conduitportion of the second body member adapted normally to close the mixtureconduit when the engine is not in operation, and vent means formed insaid gasket anterior to the throttle valve when closed connecting saidmixture conduit to atmosphere to permit the exhaust of fuel vapor afteroperation of the engine is discontinued.

2. A carburetor for an internal combustion engine including, a mixtureconduit, a first body member having a portion of the mixture conduittherein, a second body member having a portion of the mixture conduittherein, a gasket interposed between said members having an openingcorresponding with the mixture conduit portions in said members, meansinterconnecting said members, a throttle valve in the mixture conduitportion of the second body member adapted normally to close the mixturecon duit when the engine is not in operation, and a slot in 4 saidgasket anterior to the throttle valve when closed intersecting saidopening and extending outwardly therefrom to connect said mixtureconduit to atmosphere and permit the exhaust of fuel vapor afteroperation of the engine is discontinued.

3. A carburetor for an internal combustion engine including, a mixtureconduit, a first body member having a portion of the mixture conduittherein, a second body member having a portion of the mixture conduittherein, a gasket interposed between said members having an openingcorresponding with the mixture conduit portions in said members, meansinterconnecting said members, a throttle valve in the mixture conduitportion of the second body member adapted normally to close the mixtureconduit when the engine is not in operation, said gasket opening beingcircular, and a slot in said gasket anterior to the throttle valve whenclosed intersecting said circular opening and extending radially outwardtherefrom to connect said mixture conduit to atmosphere and permit theexhaust :of fuel vapor after operation of the engine is discontinued.

4. A carburetor for an internal combustion engine including, a mixtureconduit, a first body member having a portion of the mixture conduittherein, a second body member having a portion of the mixture conduittherein, a gasket interposed between. said members having an openingcorresponding with the mixture conduit portions in said members, meansinterconnecting said members, a throttle valvein the mixture conduitportion of the second body member adapted normally to close the mixtureconduit when the engine is not in operation, said gasket opening beingcircular, and a slot formed in said gasket anterior to the throttlevalve when closed intersecting said circular opening and extendingtangentially outwardly therefrom to'connect said mixture conduit toatmosphere and permit the exhaust of fuel vapor after the operation ofthe engine is discontinued.

5. In a carburetor having a mixture conduit with a throttle valvetherein, a gasket positioned between portions of the mixture conduitcomprising a one-piece member having an opening corresponding to saidconduit and vent means formed in said gasket anterior to the throttlevalve when closed connecting said mixture conduit to atmosphere.

6. In a carburetor having a mixture conduit with a throttle valvetherein, a gasket positioned between portions of the mixture conduitcomprising a one-piece member having an opening corresponding to saidconduit and a slot anterior to the throttle valve when closedintersecting said opening and extending outwardly therefrom to vent saidconduit to atmosphere.

References Cited in theifile of this patent UNITED STATES PATENTS1,767,664 Geiger June 24, 1930 2,186,480 'Ensign Jan. 9, 1940 2,683,444Miller July l3, 1954 2,684,058 Boyce July 20, 1954

